|MadSci Network: Biochemistry|
Urochrome was the original name given to the pigment thought to give urine its color. It is now known that several related pigments are responsible, so the original name has been dropped. Urine is yellow because of urobilins, specifically d-urobilin, i-urobilin, l- stercobilin, and possibly others. Urobilins are composed of four modified pyrrole rings connected by methylene bridges. Rather than try to draw them here, I will direct you to a great picture of urobilins and bilirubin from the Boehringer Mannheim Biochemical Pathways at ExPASy.
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